Integrated circuits, such as microprocessors and memory devices, include many metal-oxide-semiconductor field-effect transistors (MOSFETs), which provide the basic switching functions to implement logic gates, data storage, power switching, and the like. In one application, MOSFETs have been widely employed in Switching Mode Power Supplies (SMPS) because they are power efficient and thermally efficient. For example, a SMPS, such as a buck converter, converts an input voltage to an output voltage and supplies a load. FIG. 1 shows a conventional SMPS, which includes power switching elements SW1 and SW2 coupled in series across the input voltage source. Power switching element SW1 is coupled to the voltage supply (Vin) and power switching element SW2 is connected to ground (GND). Power switching element SW1 is also referred to as high-side (HS) switching element and power switching element SW2 as low-side (LS) switching element. Power switching elements SW1 and SW2 may be driven by a HS and a LS driver (not shown) respectively. An output filter including an inductor (L) and a capacitor (C) is connected to a junction 105 (i.e., phase node or switch node) formed by the pair of switching elements SW1 and SW2 for providing an output voltage (Vout) to a load. Through the switching elements SW1 and SW2, the output inductor L is alternately switched with one side to input voltage Vin and a ground level GND. The output voltage Vout can thus be generated to be higher or lower than the input voltage level Vin by controlling the ON and OFF actions of the switching elements SW1 and SW2 via a controller (not shown). The output voltage Vout is buffered on the capacitor C. A load (not shown) may be coupled to output node 107, and a current IL can be supplied by the inductor L to the load.
The power supply is the key element in any electronic device and its performance would affect power efficiency, product safety and product performance. Thus, it is necessary for the power supply to include a power monitoring system to understand its loading environment. Specifically, the power monitoring system may protect the power supply from overloading and short-circuit conditions by self-monitoring its current delivery. Accordingly, power monitoring systems usually need a current sensing circuit for acquiring current information.
For high-performance computing applications with SNIPS, it is essential to acquire the real-time current information for both HS and LS switching elements. The current information should include an Alternating Current (AC) portion and a Direct Current (DC) portion of the actual current supplied by the inductor to the load for accurate control, phase current sharing and power monitoring. In the recent computing applications, the conversion ratio keeps smaller and the switching frequency needs to be higher. As a result, the output current per phase gets higher. In some cases, the HS switching element may need to carry 100A current within 100 nanoseconds. However, due to diode reverse recovery, loop parasitic inductance and other issues, it becomes a challenge to accurately acquire or sense high-side current information.
It is within this context that embodiments of the present invention arise.